Strip rosemary leaves from stems, discard stems, and place leaves in the bowl of a food processor.,Add garlic and pulse until finely chopped.,Pour in the garbanzo beans; process until evenly blended.,With food processor running, slowly pour in the olive oil, scraping down sides of the bowl as necessary.,Pour in tahini, if using, then balsamic vinegar and process until evenly blended.,Taste, and add more vinegar, 1 tablespoon at a time, until desired flavor is achieved.,______,Add more water, 1 tablespoon at a time, if necessary.,Season with salt and pepper to taste.,Chill before serving.